 <!DOCTYPE html>
 <html>
    <meta name="content-type" content="text/html; charset=UTF-8">
    <head>
         <title>Calculator</title>
         
 
 <script type="text/javascript">
     var numresult;
     var str;
     
     function onclicknum(nums) {
 
         str = document.getElementById("nummessege");
         str.value = str.value + nums;
 
     }
 
     function onclickclear() {
 
         str = document.getElementById("nummessege");
         str.value = "";
 
     }
 
     function onclickresult() {
 
         str = document.getElementById("nummessege");
         numresult = eval(str.value);
         str.value = numresult;
         
     }
 </script>
 
     </head>
 
     <body bgcolor="affff" >
     
     <!--定义按键表格,每个按键对应一个事件触发-->
     
         <table border="1"
             style="height: 800px; width: 600px">
             <tr>
                 <td colspan="4">
                     <input type="text" id="nummessege"
                         style="height: 90px; width: 350px; font-size: 50px" />
                 </td>
             </tr>
             <tr>
                 <td>
                     <input type="button" value="1" id="1" onclick="onclicknum(1)"
                         style="height: 70px; width: 90px; font-size: 35px">
                 </td>
 
                 <td>
                     <input type="button" value="2" id="2" onclick="onclicknum(2)"
                         style="height: 70px; width: 90px; font-size: 35px">
                 </td>
 
                 <td>
                     <input type="button" value="3" id="3" onclick="onclicknum(3)"
                         style="height: 70px; width: 90px; font-size: 35px">
                 </td>
 
                 <td>
                     <input type="button" value="+" id="add" onclick="onclicknum('+')"
                         style="height: 70px; width: 90px; font-size: 35px">
                 </td>
             </tr>
 
             <tr>
                 <td>
                     <input type="button" value="4" id="4" onclick="onclicknum(4)"
                         style="height: 70px; width: 90px; font-size: 35px">
                 </td>
 
                 <td>
                     <input type="button" value="5" id="5" onclick="onclicknum(5)"
                         style="height: 70px; width: 90px; font-size: 35px">
                 </td>
 
                 <td>
                     <input type="button" value="6" id="6" onclick="onclicknum(6)"
                         style="height: 70px; width: 90px; font-size: 35px">
                 </td>
 
                 <td>
                     <input type="button" value="-" id="sub" onclick="onclicknum('-')"
                         style="height: 70px; width: 90px; font-size: 35px">
                 </td>
             </tr>
 
             <tr>
                 <td>
                     <input type="button" value="7" id="7" onclick="onclicknum(7)"
                         style="height: 70px; width: 90px; font-size: 35px">
                 </td>
 
                 <td>
                     <input type="button" value="8" id="8" onclick="onclicknum(8)"
                         style="height: 70px; width: 90px; font-size: 35px">
                 </td>
 
                 <td>
                     <input type="button" value="9" id="9" onclick="onclicknum(9)"
                         style="height: 70px; width: 90px; font-size: 35px">
                 </td>
 
                 <td>
                     <input type="button" value="*" id="mul" onclick="onclicknum('*')"
                         style="height: 70px; width: 90px; font-size: 35px">
                 </td>
             </tr>
 
             <tr>
                 <td colspan="2">
                     <input type="button" value="0" id="0" onclick="onclicknum(0)"
                         style="height: 70px; width: 190px; font-size: 35px">
                 </td>

 
                 <td colspan="2">
                     <input type="button" value="/" id="division"
                         onclick="onclicknum('/')"
                         style="height: 70px; width: 90px; font-size: 35px">
                 </td>
             </tr>
 
             <tr>
 
 
                 <td colspan="4">
                     <input type="button" value="=" id="result"
                         onclick="onclickresult()"
                         style="height: 70px; width: 190px; font-size: 35px" />
                 </td>
 
 
             </tr>
 
 
         </table>
 
     </body>
 </html>
